This invention relates to a field of flow control valves for particulate material. More specifically, it relates to flow control valves for magnetic abrasives such as steel shot, grit, and the like, or mixtures of magnetic abrasives and nonmagnetic abrasives wherein the magnetic abrasives constitute on the order of at least 50% of the mixture. Such particulate materials are utilized in many industrial applications for cleaning, abrading, preening, and otherwise treating surfaces. Often the particulate is projected against the surface to be treated by an abrasive throwing wheel as, for example, the airless centrifugal throwing wheels manufactured by Wheelabrator-Frye of Mishawaka, Indiana.
In providing a flow of particulate matter to such devices it is often necessary to employ flow control valves to regulate or, when necessary, completely stop the flow of abrasive from a supply hopper to a projection device. In many instances large heavy-duty flow valves are desirable and are known. However, in certain specific applications, it is necessary to provide miniaturized valves and in particular valves which are highly efficient and not subject to the usual mechanical wear problems.
It is accordingly an object of the present invention to provide an improved flow valve construction which is small in size and which can be employed for regulating the flow of particulate which includes a substantial portion of magnetic particles.
It is a further object of the invention to provide a flow control valve which does not require a complete mechanical seal and which has very low wear characteristics resulting therefrom.
It is another object of the invention to provide a flow control valve which employs magnetic flux fields as the controlling force for regulating particulate flow.
Other objects and advantages of the present invention will be apparent from the remaining portion of the specification.